Liquid crystal display device having pole spacers formed over optical shield film

ABSTRACT

A method for forming a liquid crystal display device includes forming a metal film over a drive substrate, and patterning the metal film to form at least one pixel electrode and an optical shield film. The optical shield film is provided outside of a pixel electrode area and has a width greater than a width of each of the pixel electrode. A resin is deposited over the patterned metal film, and the resin is patterned to form at least one pole spacer and strip spacer. The strip spacer surrounds the pixel electrode area and has a width greater than a diameter of each of pole spacer. Liquid crystal material is supplied into an inside space which is surrounded by the strip spacer, and a sealing material is filled at outer edges of the strip spacer for fixing the drive substrate and a common substrate.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 09/370,245, filedAug. 9, 1999, now U.S. Pat. No. 6,304,308 the subject matter of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to liquid crystal displaydevices; and, more particularly, the invention relates to a liquidcrystal display device that maintains a uniform gap for a liquid crystallayer, to a liquid crystal display device that can prevent opticalleakage in the display area, and to a liquid crystal display device thatcan prevent pollution in the liquid crystal composite material by theseal agent.

Recently, display devices using a liquid crystal panel have become morewidely employed as display devices which are capable of visuallyproducing high-precision color images adaptable for use in displaydevices of the projection type, in notebook personal computers, inmonitor units and in other similar visual representation instruments.

Currently available display devices using such a liquid crystal panel(liquid crystal display devices) typically include those of the simplematrix type, which make use of a liquid crystal panel having a liquidcrystal layer sandwiched between a pair of substrates with parallelelectrodes formed on respective inner surfaces in a mutual crossoverfashion, and other panels of the active matrix type which employ aliquid crystal element (referred to also as “liquid crystal panel”hereinafter) that has switching elements for selection in units ofpixels on only one of the pair of substrates.

Active-matrix liquid crystal display devices are generally categorizedinto two groups: one group includes certain liquid crystal displaydevices of the so-called vertical electric-field type typicallyincluding the twisted nematic (TN) scheme (also known as TNactive-matrix liquid crystal display devices) configured to include anensemble of pixel selection electrodes formed on each of a pair of upperand lower substrates, and a second group includes the so-called “lateralelectric-field” liquid crystal display devices (generally calledin-plane field type IPS liquid crystal display devices) using a specificliquid crystal panel with pixel select electrodes formed on only one ofa pair of upper and lower substrates.

Projection liquid crystal display devices are also known as one type ofliquid crystal display device application equipment. Projection liquidcrystal display devices include an optical system for magnification ofan image generated on a liquid crystal panel of small size to provide anenlarged image which is then projected onto a spaced-apart second screenof large size. Such projection liquid crystal display devices includedevices of the transmission type and those of the reflection type, theformer being designed such that two separate dielectric substratesmaking up a liquid crystal panel are both formed of transparentsubstrates, such as glass substrates by way of example, for permittingrays of light to be emitted from the back surface thereof to therebycause resulting modulated transmission light images to be projected withenlarged sizes on an associative screen by use of an optical lens orcombination thereof. On the other hand, the reflective projectors employone of such dielectric substrates as a reflector plate for emittinglight from the surface side to thereby produce an image which consistsof modulated reflected light, which in turn is projected by an opticalsystem on a screen with a magnified scale.

There are also display devices for use with notebook PCs or direct viewliquid crystal display devices for display monitors, which are designedto employ as a reflector plate either one of the dielectric substratesmaking up the liquid crystal panel and which utilizes incoming lightfrom the display surface side.

Typically, a liquid crystal panel constituting such a liquid crystaldisplay device is arranged so that a liquid crystal layer made of achosen liquid crystal material is sandwiched in a gap between twoseparate dielectric substrates which are bonded together, such as glasssubstrates, for example, and thereafter the peripheral edges thereof aresealed using a chosen seal material. The gap between two dielectricsubstrates is narrow and typically will measure less than 4 to 7micrometers (μm) for instance, which gap will be collectively referredhereinafter as a “cell gap”. One prior known method of retaining thiscell gap is to randomly distribute spherical spacers of substantiallyuniform diameter, sometimes called beads, between the substrates.

Although controllability of the cell gap may readily be enhanced byincreasing the requisite number of beads that are distributed, thedistribution amount has generally been set at 150 pieces per squaremillimeter in view of the fact that random distribution of such beadsinherently lacks uniformity thereby making it very difficult tocompletely prevent some beads from locally crowding together at alocation. This can result in an increase in the number of opticaldot-like dislocations, and the random bead distribution also causes anadverse reaction, such as creation of an undesired disturbance in thealignment of the liquid crystals near or around such beads, which wouldresult in a contrast reduction becoming greater locally.

While the beads may be made of an organic polymer or quartz, use ofquartz beads can cause destruction of any one of the protective films,the electrodes, and the switching elements, such as TFTs, which arefabricated on a dielectric substrate at a press-machining step forestablishment of the cell gap, or alternatively result in unwantedcreation of air holes or “bubbles” with a change in temperature due to adifference in the thermal expansion coefficient between the beads and aliquid crystal material being used. For this reason organic polymerbeads are employed in most cases.

In direct-view liquid crystal display devices, the beads which aredistributed often attempt to move or “drift” upon application of astress to the dielectric substrate. In this respect, it will bedesirable for the liquid crystal layer to be kept at negative pressuresrelative to the atmospheric; however, presently available manufacturingtechnologies make it difficult to constantly maintain such a state inwhich the liquid crystal panel products are constantly held in anegative pressure condition.

On the other hand, small size liquid crystal display devices for use inprojector equipment are burdened with a problem in that certain beadsdistributed between dielectric substrates of its liquid crystal panel,which reside in the panel's display area, can unintentionally beprojected on a screen as a magnified shadow image, which in turn resultsin a decrease in the quality of the picture images being displayed. Oneprior known approach to avoiding such image quality reduction is toemploy what is called a “beads-less” scheme which uses a limited numberof beads or fibers only at the periphery of the liquid crystal panel'sdisplay area to thereby retain the intended cell gap at such peripheryonly. Unfortunately, this beads-less approach suffers from a difficultyin maintaining the cell gap in the display area at a predeterminedvalue, which can result in a decrease in the production yield and inimage quality.

Further, in recent years, high-speed image displayability has beendemanded, which in turn calls for establishment of so-called “narrowgap” designs for further reduction of cell gaps with increased gapcontrol accuracies of 0.1 μm or below. As such narrow-gap designs arebecoming more important, a need is felt to further increase thebead-spacer machining accuracy, which however is very difficult,especially in prior art reflective liquid crystal panels, whereinachievement of such high machining accuracy remains extremely difficultdue to the fact that the cell gaps are nearly half the size of those inthe devices of the transmission type.

One proposed approach to avoiding the cell-gap problem is to form, byphotolithography techniques, columnar or pillar-shaped spacers (referredto hereinafter as “pole-like spacers”) on a dielectric substrate atselected locations (certain portions that do not affect displayability,such as portions between adjacent pixels or alternatively thoseimmediately underlying a black matrix) in the display area thereof,which spacers provide support between the two dielectric substratesstacked over each other to thereby render the cell gap uniform.

Use of such pole-like spacers eliminates local crowding and unwanteddrift movement of distributed beads. Furthermore, as the fabricationaccuracy of photolithography is significantly greater than the machiningaccuracy of beads by one order of magnitude or greater, the height ofthe pole spacers is simply determinable depending upon the thickness ofthe deposited photoresist film constituting these pole spacers, which inturn makes it possible to noticeably improve the cell gap accuracy.

SUMMARY OF THE INVENTION

Unfortunately, currently available photoresist materials can dissolveinto a liquid crystal material, so as to undesirably reduce theelectrical resistivity of the liquid crystal layer, which would resultin a decrease in co-useability or “congeniality” with respect to theliquid crystal materials. Alternative use of inorganic materialstherefor can result in a mismatch of the thermal expansion coefficientwith the liquid crystal layer. All in all, no optimal materialsadaptable for use in fabricating the intended spacers have been reportedto date.

One typical prior known approach to controlling the cell gap is to mixeither fibers or beads made of organic polymer or quartz as a fillerinto a seal material being deposited at the outer periphery of a displayarea. However, this approach also creates a problem in that the use of aquartz filler(s) can result in destruction of the lead terminalelectrodes and/or switching circuitry, as in the case of employing beadsdistributed within the display area. While it is also consideredeffective to coat a seal material at specific portions lying outside ofa switching circuitry formation region of the display area, thisinherently creates a serious problem in that the resulting liquidcrystal panel increases in size due to a need to reserve an extra areafor seal portions. Another problem encountered in the prior art isdifficultly in improving the accuracy of the cell gap because of thefact that organic polymer beads are readily collapsible; and, in view ofthis, it is a general approach to employ fibers for the seal portions.

A known sealing method includes the steps of coating, by use of screenprinting techniques or using dispensers or the like, one of twodielectric substrates with a filler-mixed seal material in a selectedregion along the outer periphery of its display area, laminating theother dielectric substrate over the seal material-coated substrate,pressing these substrates together at increased pressures to permit theseal material sandwiched therebetween to sheet against the substratesurface for establishment of the intended cell gap, and then hardeningthe seal material sheet. A disadvantage of this method is that itremains impossible, or at least greatly difficult, to attain therequired accuracy of position alignment at the seal edge portions, whichresults in the seal portions becoming irregular in shape. An opticalblocking or shielding means must be additionally provided to precludeunintentional visualization of such an irregular seal edge shape.Especially with small size liquid crystal panels, use of such opticalshield means can result in an increase in the surface area for use insealing.

An object of the present invention is to provide an improved liquidcrystal display device which is capable of eliminating displayirregularities by avoiding random behavior (either local crowing ordrift movement) of beads in a display area which can occur when usingbeads, as well as destruction of switching elements and electrodes orthe like due to presence of fillers contained in beads or sealmaterials, along with cell gap differences in the liquid crystal paneloccurring in the display area and at sealed portions, while at the sametime enabling achievement of high-quality displayability by precludingcontamination of a liquid crystal material due to unwanted contactbetween the seal material and the liquid crystal layer.

To attain the foregoing object the present invention, spacpes are formedphotolithographically both in a display surface area of one dielectricsubstrate of a liquid crystal panel constituting the liquid crystaldisplay device and at sealed portions thereof at the same time. Thespacers formed within the display area are comprised of columnar orpole-like spacers while those formed at the sealed portions consists ofa zonal or band-shaped spacer which has a width which is greater thanthe diameter of such pole spacers. A chosen sealing material containingno fillers therein is deposited or coated at the outer periphery of thiszonal spacer, which material is later hardened, thus allowing bothsubstrates to be tightly bonded together.

With regard to the embodiments disclosed herein, some representativeaspects of the invention will be summarized below.

A liquid crystal display device in accordance with the instant inventionis arranged to include a first substrate having thereon a great numberof pixel electrodes in the form of a matrix, a second substrate opposingsaid first substrate with a predefined gap defined between them, aliquid crystal layer made of a liquid crystal composition materialsealed into the gap between said first and second substrates, and anoptical alignment film formed on at least one of said first and secondsubstrates in contact with said liquid crystal layer for controlling theoptical orientation or alignment of said liquid crystal material,wherein the device further includes a plurality of columnar or pole-likespacers formed in the display surface area of said first substrate forretaining the size of said gap between said first and second substratesat a preselected value, while also including a zonal or band-shapedspacer made of the same material as that of said pole-like spacers forsurrounding said display area and having a width greater than thediameter of said pole-like spacers, with a seal material being filled atthe outer periphery of said strip-like spacer for tightly bonding saidfirst and second substrates together. Note that providing the bandspacer avoids the necessity for the seal material to contain thereinbeads or fibers or any equivalents thereto for use in controlling thegap between the two substrates.

With such an arrangement, the spacer's inherent random behavior withinthe display area may be suppressed or eliminated, thereby retaining amore uniform resultant cell gap. Another advantage is that the sealmaterial will no longer come into contact with the liquid crystal layerthus precluding contamination of the liquid crystal material due to thepresence of seal material, which in turn makes it possible to avoiddestruction of the electrodes and the like due to the beads in thedisplay area or alternatively destruction of electrode extension leadsand the like at the sealed portions due to presence of fillers mixedinto the seal material, thus improving the production yields and thereliability.

A further advantage is that the pole spacers stay equal in height to theband spacer with an increased accuracy to thereby enable the cell gap tobe well controlled to a high accuracy over almost all regions of thedisplay area, which in turn makes it possible to eliminate visualizationirregularities during displaying of on-screen images, including flutter,moire, streaking, and pixel jitter at certain intensities.

Additionally the present invention should not be limited only to theabove-noted arrangements and may alternatively be modified and alteredin a variety of different forms without departing from the technicalconcept of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating, in cross-section, a liquid crystalpanel of a liquid crystal display device in accordance with oneembodiment of the present invention.

FIG. 2 is a diagram depicting a plan view of the liquid crystal panelshown in FIG. 1 for explanation of a layout of columnar spacers and azonal spacer thereon.

FIG. 3 is a microphotograph-based pictorial representation of a planview of one typical columnar spacer in accordance with the invention.

FIG. 4 is a diagram showing a plan view of a liquid crystal panel of aliquid crystal display device in accordance with a second embodiment ofthe invention, for explanation of a layout of columnar spacers and azonal spacer thereon.

FIG. 5 is a diagram showing a plan view of a liquid crystal panel of aliquid crystal display device in accordance with a third embodiment ofthe invention, for explanation of a layout of columnar spacers and azonal spacer thereon.

FIG. 6A is a plan view and FIG. 6B is a cross-section on line VIB—VIB inFIG. 6A, showing an overall configuration of a projection-type liquidcrystal display device incorporating an actually implemented-liquidcrystal display device of the invention.

FIG. 7 is a diagram schematically depicting one exemplary structure ofthe projection liquid crystal display device employing the liquidcrystal display device shown in FIG. 6.

FIG. 8 is a plan view diagram of a liquid crystal panel constituting anactive-matrix liquid crystal display device also incorporating theprinciples of the invention.

FIG. 9 is an enlarged partial plan view diagram of the liquid crystalpanel shown in FIG. 8 showing the upper left part thereof and its nearbyportions with a seal section SL provided thereon.

FIGS. 10A, 10B and 10C are diagram showing in cross-section main partsof a liquid crystal panel constituting the active-matrix liquid crystaldisplay device embodying the invention.

FIG. 11 is an exploded perspective view of a direct-view liquid crystaldisplay apparatus employing a liquid crystal display device of theinvention.

FIG. 12 is a perspective view of a notebook computer for explanation ofone embodiment of the liquid crystal display device of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained indetail with reference to the accompanying drawings.

Referring now to FIG. 1, there is illustrated in schematic cross sectiona liquid crystal panel in accordance with one embodiment of the instantinvention. This liquid crystal panel is a reflective liquid crystalpanel adaptable for use in projection liquid crystal display devices,wherein reference character “USUB” designates an upper-side substrate(opposed substrate) representing a first substrate; DSUB denotes alower-side substrate (drive substrate) representing a second substrate;LC indicates a liquid crystal layer made of a chosen liquid crystalcomposition material; SUB2 represents the glass substrate making up theopposed substrate; ITO-C specifies a transparent electrode (commonelectrode, or alternatively opposed electrode); ORI2 shows an upper-sideoptical orientation or “alignment” film; SUB1 is a single-crystallinesilicon substrate constituting the drive substrate; AL- P denotes pixelelectrodes; ORI1 denotes a lower alignment film; TM denotes a terminalsection; PSV1 denotes a protective film; SPC-P denotes columnar orpole-like spacers; SPC-S denotes zonal or band strip-shaped spacers; SLdenotes a sealing material; and SHF denotes a light shield film.

It should be noted that the illustrated liquid crystal panel is assumedto be of the active matrix type, and that this panel also includesswitching elements for pixel selection and storage capacitors or thelike, not shown, on the drive substrate DSUB along with the pixelelectrodes AL-P shown in FIG. 1.

The liquid crystal layer LC is sealed and sandwiched between the opposedsubstrate USUB with the opposed electrodes ITO-C and alignment film ORI2formed thereon and the drive substrate DSUB on which the pixelelectrodes AL-P and protective film PSV1 plus alignment film ORI1 areformed. The drive substrate DSUB is associated with the columnar orpole-like spacers SPC-P which are formed on the protective film PSV1 atselected locations excluding those of the pixel electrodes and also withthe zonal or band strip-shaped spacer SPC-S that is placed at thebonding periphery the both substrates; that is, along the outerperipheral sides of a display surface area with the pixel electrodesAL-P and the like formed therein. The strip-like spacer SPC-S isdesigned to have a predefined width that is greater in size or dimensionthan the diameter of the pole spacers SPC-P to thereby receive thecompressive pressures which are applied when the two substrates arebonded and pressed together during assembly for accurately retaining acell gap between the substrates at the periphery thereof whilecontrolling the cell gap of the display area, so that the gap is held ata predefined value in cooperation with the pole spacer SPC-P.

More specifically, upon pressing both substrates together, the resultantgap space, i.e. the cell gap of the liquid crystal layer, may beaccurately controlled by the height of the pole spacers SPC-P and stripspacer SPC-S. And, sealing the liquid crystal layer into the displayarea or region may be achieved by a method that includes the steps ofdripping a liquid crystal composition into the display region prior tolamination of the substrates and then pressing the laminated substrateswhen bonding them together while permitting outward draining of anyextra liquid crystal material; or, alternatively, by another methodincluding the steps of forming in advance or “preforming” an opening atpart of the strip spacer SPC-S, superposing the substrates over eachother, coating a chosen seal material containing therein no fillersalong the outer edges of the strip spacer SPC-S, irradiating ultravioletrays for effecting half-hardening thereof, injecting a liquid crystalmaterial from the opening, while setting the atmosphere at a negativepressure, and thereafter effectuating pressing and thermal treatment forcomplete hardening of the seal material SL to thereby establish therequired cell gap.

Note that, although not specifically illustrated in the drawing, in thecase of a projection liquid crystal display device, the terminal sectionTM is connected to those terminals of a flexible printed circuit boardfor use in coupling electrical signals for driving the involvedswitching elements.

FIG. 2 is a diagram showing a plan view of the liquid crystal panelshown In FIG. 1 for explanation of the planar layout pattern of the polespacers and strip spacer. The layout of these spacers is indicated inpositional relation with respect to the pixel electrodes associatedtherewith.

The pole spacers SPC-P that are to be formed in the display area areprovided at crossover locations among the pixel electrodes AL-P. In thisembodiment, providing the pole spacers SPC-P in the spaces betweenadjacent pixel electrodes precludes significant reduction of theaperture ratio. In addition, since it is possible to provide the polespacers SPC-P one by one in all the spaces among pixel electrodes, theresulting setup number of such spacers is increased by one order ofmagnitude or greater when compared to the case of using beads to therebypermit achievement of enhanced cell gap controllability, which in turnguarantees that any positional deviation or misalignment will no longertake place between the two substrates.

The strip spacer SPC-S is formed to overlie the optical shield film SHFat the outer periphery of the display area. The optical shield film SHFis formed by the same layer as the pixel electrode. This strip spacerSPC-S is so formed as to surround the outer periphery of the displayarea while its width is greater than the diameter of the pole spacersSPC-P. And, this strip spacer SPC-S has the function of sealing theliquid crystal layer LC while allowing the seal material, this hastraditionally been disposed in contact with the liquid crystal layer tobe coated at the outer periphery of the strip spacer SPC-S.

An explanation will next be given of a method of forming the polespacers and the strip spacer in the illustrated embodiment.

In the embodiment, the pole spacers and the strip spacer are made of achosen material, such as, for example, the chemical amplificationnegative-type resist “BPR-113” (trade name) manufactured by KabushikiKaisha JRS. This resist material is comprised of a specific materialwhich is very similar to those materials which have been employed forbead spacers in prior art liquid crystal panels, in that the materialwill hardly attempt, after having hardened, to dissolve into the liquidcrystal material, nor exhibit imbibition or swelling activities whilesimultaneously offering increased adaptability or congeniality with suchliquid crystal material, with the machinability also being enhanced.

FIG. 3 is a pictorial representation of the shape of a typical one ofthe pole spacers used in the embodiment, which has been prepared byillustrative duplication to mimic a corresponding microphotographthereof. The pole spacer shown herein has been fabricated into a goodshape at a crossing point or “intersection” of the spacers SSP betweenthe pixel electrodes AL-P.

The “BPR-113” that becomes the material of the pole spacers and stripspacer is deposited by spin coat techniques on the protective film PSV1(see FIG. 1) of the drive substrate DSUB with the pixel electrodes AL-Pformed thereon; then, the resultant structure is irradiated with i-rays;and next, development for fabrication is effected.

The liquid crystal material is injected into the space surrounded by thestrip spacer SPC-S of the drive substrate DSUB with the pole spacers andstrip spacer formed thereon. In the case where the strip spacer SPC-Shas the shape as shown in FIG. 2, the liquid crystal material droppedinto the space. The common substrate USUB is positioned while preventingit from coming into contact with the upper part of this drive substrateDSUB; and then, de-gas processing is carried out. After having removedany gases, both substrates are laminated over each other and are thenprocessed together at increased pressures for tight contact with eachother. At this time, any extra components of the liquid crystal materialbehave to overflow or extrude out of the strip spacer SPC-S. These extraextruded liquid crystal material components are washed out; then, theseal material SL that contains no fillers is deposited along the outeredges of the strip spacer SPC-S and between both substrates and is thenhardened.

In the illustrative embodiment, use of the pole spacers SPC-P and thestrip spacer SPC-S fabricated under the same conditions ensures that thecell gap in the display area is equal to that at the sealed portions,which in turn makes it possible to eliminate undesired creation ofdisplay image irregularities otherwise occurring due to any possiblecell gap differences. In addition, the liquid crystal materialconstituting the liquid crystal layer LC will no longer come in directcontact with the seal material being used, which in turn enablespreclusion of contamination of the liquid crystal material due to thepresence of a non-hardened or uncured part of the seal material; and inaddition, it is no longer required that the seal material containfillers therein, which guarantees that the electrode extension terminalsare hardly open-circuited, while minimizing the risks of destruction ofother thin-films.

FIG. 4 depicts a plan view of a liquid crystal panel used in a liquidcrystal display device in accordance with a second embodiment of thisinvention, which panel has on its surface pole spacers and a stripspacer formed into a planar pattern as shown herein. This embodiment isarranged so that a gap is provided at part of the strip spacer SPC-Sformed at the outer periphery of the display area for use as a liquidcrystal injection port INJ. The remaining arrangement of the embodimentis similar to that of said first embodiment and thus a furtherexplanation thereof will be omitted herein. A manufacturing method ofthe liquid crystal panel of this embodiment will be explained below.

Fabrication of the drive substrate DSUB may be similar in principle tothat of said first embodiment except that a process step is added ofproviding the liquid crystal injection port INJ in the strip spacerSPC-S. The opposed substrate USUB is bonded to this drive substrateDSUB; and then, the substrate are pressed together at high pressures tothereby bring these substrates into tight contact with each other. Underthis condition, the atmosphere is pressure-reduced for gas removal; andthen, the liquid crystal material is injected thereinto from the liquidcrystal injection port INJ. Thereafter, a chosen seal material isdeposited along the outer edges of the strip spacer SPC-S including theliquid crystal injection port INJ; and then, it is allowed to harden.

Alternatively, a similar seal material may be deposited at the liquidcrystal injection port INJ for sealing prior to deposition of the sealmaterial at the outer edges of the strip spacer SPC-S. Note that theliquid crystal injection port INJ may be replaced with an array of twoor more liquid crystal injection ports INJ where appropriate. Thepresent embodiment is capable of attaining similar effects andadvantages to those of said first embodiment.

It is noted that, although in both of the respective embodimentsreferred to above, the drive substrate DSUB has been described to be ofthe reflection type using a single-crystalline silicon substrate, asimilar arrangement may also be achieved either in the case of liquidcrystal display devices of the transparent type with both substratesformed as glass substrates or in the case of direct-view liquid crystaldisplay devices with large display screen areas.

FIG. 5 is a plan view of a liquid crystal panel used in a liquid crystaldisplay device in accordance with a third embodiment of this invention,for explanation of the layout of pole spacers and a strip spacerthereon. This embodiment is arranged such that a built-in driver circuitDCT is directly mounted on the drive substrate DSUB at a locationoutside of the display surface area thereon, while letting the stripspacer SPC-S be formed overlying this driver circuit DCT. The polespacers SPC-P are similar in nature to those in the first embodiment.

With this embodiment the same effects and advantages as those of theabove-noted respective embodiments are obtainable; and additionally, itis possible to achieve a small-area liquid crystal display device as awhole because of the fact that a space for driver circuitry to bemounted. externally of the liquid crystal panel may be omitted.

An explanation will next be given of some examples which are obtainableby implementation of each embodiment stated supra. FIGS. 6A and 6B showan overall arrangement of a liquid crystal display device of theprojection type employing an actually implemented example of the liquidcrystal display device in accordance with the invention, wherein FIG. 6Ais a partly cutaway plan view, whereas FIG. 6B is a cross-section takenalong line VIB—VIB of FIG. 6A.

As shown in the drawing, this projection liquid crystal display deviceis arranged to have on its second substrate DSUB multiple pole-likespacers SPC-P and a strip spacer SPC-S With a liquid crystal layer LCsandwiched between a first substrate USUB and the second substrate DSUBfor controlling the required cell gap using the pole spacers SPC-P andthe strip spacer SPC-S. The reflective liquid crystal panel having aseal material SL coated along outer edges of the strip spacer SPC-S,which is then hardened for tightly bonding both substrates together, isreceived inside of the cavity of a package PCG. The package PCG maypreferably be constituted from a mold-machined product made of resinmaterials, and a flexible printed circuit board FPC for use in supplyingone or more signals along with electrical power to one edge thereof isconnected thereto at its one end. The package PCG is provided with asurface glass WG employed for covering the cavity to thereby provide asealed environment therein.

A heat release or heat sink plate PPB made of a chosen metal is disposedon the back surface of the package PCG in a manner such that the heatsink has its peripheral portions embedded therein at four lower sides ofthe package main body PCG while letting the liquid crystal panel bereceived With a comparatively elastic or resilient heat radiator sheetDPH placed between it and the heat sink PPB. Accordingly, the backsurface of the liquid crystal panel comes into tight contact with theheat sink PPB via the heat radiator sheet DPH to thereby provide theintended structure with enhanced heat radiation effects.

The liquid crystal panel that is housed inside of the cavity of thepackage PCG is fixed by adhesive ADH to a step-like portion on the backside of the first substrate USUB thereof, which portion is formed at theinner periphery on the bottom of this package PCG, while the surfaceglass WG is adhered to a space plate SPB for fixing the package PCG andflexible printed circuit board FPC together. Note here that the spaceplate SPB is bonded to the flexible printed circuit board FPC byadhesive, not shown.

FIG. 7 is a pictorial representation for explanation of one exemplaryconfiguration of a projection liquid crystal display device using theliquid crystal display device that has been explained in conjunctionwith FIG. 6, which includes housing, CAS a liquid crystal display device(liquid crystal module) MOD, illumination light source LSS, illuminationlens system LNS, first optical polarizer plate POL1, reflection mirrorMIL, focusing lens system FLN, second optical polarizer plate POL2,optical diaphragm or iris ILS, and image-projection optical system PLN.

Illumination light from the light source device LSS is guided by theillumination lens system LNS and first polarizer plate POLI plusreflection mirror MIL to the surface of the liquid crystal panel PNLconstituting the liquid crystal display device MOD. Light which arrivesat the liquid crystal panel PNL is then subjected to modification in away corresponding to an image signal at the pixel electrode of theliquid crystal panel PNL to thereby provide refection light which ismagnified for projection onto the screen SCN by way of the focussinglens system FLN and second polarizer plate Pd2 plus iris ILS as well asprojection optical system PLN.

An explanation will next be given of an example which applies theinvention to a direct-view liquid crystal display device in terms of anactive-matrix liquid crystal display device.

FIG. 8 is a diagram showing a plan view of a liquid crystal panelconstituting the active-matrix liquid crystal display device, whichdepicts a main part around a matrix AR of a liquid crystal panel PNLincluding upper and lower transparent glass substrates SUB2 (colorfilter substrate), SUB1 (active-matrix substrate) which constitute thefirst and second substrates; and FIG. 9 is an enlarged plan view of partnear a seal section corresponding to the upper left corner portion ofthe liquid crystal panel shown in FIG. 8.

In addition, FIGS. 10A, 10B and 10C are diagrams showing incross-section main portions of the liquid crystal panel, wherein FIG.10A is a sectional view taken along line 19 a—19 a of FIG. 9, FIG. 10Bis a sectional view of a TFT section, and FIG. 10C is a sectional viewnear an external connection terminal DTM to which image signal linedriver circuitry is to be connected.

In the manufacture of this liquid crystal panel, if it is of small size,then a single glass substrate is subject to simultaneous processing of aplurality of panels at one time and is the substrate then separated intoplural pieces for throughput improvement; alternatively, if it is largein size, then a specific glass substrate having its size standardizedfor common use with a variety of types of products is employed which isso processed and then made smaller into a proper size accommodatingrespective types of products for purposes of shared use of theproduction facility; in either case, the glass substrate is cut afterhaving completed a series of specified process steps.

FIGS. 8 and 10 show the state after having completed a cut-off processof the upper and lower substrates SUB2, SUB1; whereas, FIG. 9 shows thestate prior to the cutoff process, wherein LN designates the edge of acut line of such glass substrate, and CT1 and CT2 denote certainpositions at which the glass substrates SUB1, SUB2 are to be cut,respectively.

In either case, the finally manufactured state is such that at thoseportions whereat external connection terminal groups Tg, Td (suffixomitted) are located, the upper-side glass substrate SUB2 is limited insize so that it exists inside of the lower-side glass substrate SUB1 tothereby allow the terminal groups to be exposed to the outside.

The external connection terminal groups Tg, Td are such that a pluralityof components consisting essentially of scan circuit connectionterminals GTM and image signal circuit connection terminals DTM alongwith electrical extension leads associated therewith are organized intoa group in units of tape carrier packages with driver circuits mountedthereon. Those extension leads of each group extending from the matrixsection up to the external connection terminal unit are so designed asto become slanted or tilted as they come closer to both ends. This isaimed at positional alignment of the terminals DTM, GTM of the liquidcrystal panel PNL with the connection terminal pitch at respective tapecarrier packages.

Pole spacers SPC-P are formed in the display area AR between thetransparent glass substrates SUB1, SUB2 whereas a strip spacer SPC-S isformed in the seal section thereof along its edges, excluding the liquidcrystal seal injecting portion INJ, in a such a manner as to seal theliquid crystal LC. And, a seal material SL is coated at the outer edgesof the strip spacer SPC-S. This seal material is made of an epoxy resin,for example. Note that the pole spacers SPC-P are not visible in FIG. 10because they are formed at the boundaries of pixels.

A common transparent pixel electrode ITO2 on the upper transparent glasssubstrate SUB2 is connected by a silver paste material SGP at least atone portion; here, at four corner edges of the liquid crystal panel toan extension lead INT that is formed on the lower transparent glasssubstrate SUB 1. This extension lead INT is fabricated simultaneouslyduring formation of gate terminals GTM and drain terminals DTM.

Respective layers of alignment films ORI1, ORI2 and transparent pixelelectrodes ITO1 plus common transparent pixel electrodes ITO2 are formedinside of the strip spacer SPC-S. Polarizer plates POL1, POL2 are formedon outer surfaces of the lower transparent glass substrate SUB1 andupper transparent glass substrate SUB2, respectively.

Liquid crystal LC is sealed in the display area AR which is partitionedby the strip spacer SPC-S between the lower alignment film ORI1 andupper alignment film ORI2. The lower alignment film ORI1 is formed on aprotective film PSV1 on the side of the lower transparent glasssubstrate SUB1.

This liquid crystal panel PNL is assembled through process steps ofindividually stacking various layers over each other on each side of thetransparent glass substrate SUB1 and transparent glass substrate SUB2,laminating the lower transparent glass substrate SUB1 and the uppertransparent glass substrate SUB2 over each other, injecting a chosenliquid crystal material via the opening INJ (liquid crystal sealinjection port) of the strip spacer SPC-S, thereafter sealing using theseal material SL, and then cutting the upper and lower transparent glasssubstrates.

A thin-film transistor TFT as shown in FIGS. 10A, 10B and 10C operatesin a way such that, upon application of a positive bias to its gateelectrode GT, the channel resistivity between the source and drainthereof decreases; alternatively, the source-drain resistivity increaseswhen the bias is set at zero.

The thin-film transistor TFT of each pixel is divided into two portions(plural parts) within the pixel. In FIG. 10B only one of them isdepicted. Each of the two thin-film transistors TFT is arranged to havesubstantially the same size (equal in channel length and in channelwidth). Each of such divided thin-film transistors TFT has a gateelectrode GT, gate insulation film GI, i-type semiconductor layer ASmade of intrinsic amorphous silicon (Si) with no conductivity typedetermination impurities doped therein, and a pair of source electrodeSD1 and drain electrode SD2. Note here that the source and drain areinherently determined depending on the bias polarity between them, andthat such polarity will possibly be inverted in this liquid crystaldisplay device so that the source and drain are interchangeable innature. In the following explanation however, one of them is fixedlyrepresented by the source with the other called the drain for purposesof convenience in the discussion herein.

The gate electrode GT is designed to extend beyond respective activeregions of the thin-film transistor TFT while respective gate electrodesGT of the thin-film transistors TFT are formed continuously. Here, thegate electrode GT is formed of a single-layer second conductive film g2.The second conductive film g2 may be made for example of an aluminum(Al) film as formed by sputtering techniques to a predeterminedthickness ranging from 1,000 to 5,500 Angstroms Å. In addition, ananodized film AOF of aluminum is provided on the gate electrode GT.

This gate electrode GT is formed to have a slightly larger size than thei-type semiconductor layer AS to thereby completely cover it (whenlooking from the lower side thereof). Accordingly, in case a backlightBL, such as a fluorescent tube, is attached to the lower part of thelower transparent glass substrate SUB1, the gate electrode GT consistingof such opaque aluminum film serves to block rays of light emitted fromthe backlight BL thus preventing the light from falling onto the i-typesemiconductor layer AS, which in turn makes it possible to minimize thepossibility of conduction phenomena due to light irradiation, i.e.reduction of the turn-off characteristics of the thin-film transistorTFT. Additionally, the inherent size of the gate electrode GT is suchthat it has a width minimally required to allow the gate electrode tospan or “bridge” between the source electrode SD1 and drain electrodeSD2 (also including margins for position alignment between the gateelectrode GT and the source and drain electrodes SD1, SD2) whereas thedepth thereof which determines the resultant channel width W isdeterminable depending on how the ratio of it to a distance (channellength) L between the source electrode SD1 and drain electrode SD2;namely a factor W/L determining the mutual conductance ortransconductance gm is designed. Obviously the actual size of the gateelectrode GT in this liquid crystal display device is made greater thanthe inherent size noted above.

Scan signal lines are constituted from a second conductive film g2. Thissecond conductive film g2 of such scan signal lines is fabricatedsimultaneously during formation of the second conductive film g2 of gateelectrodes GT while allowing the former to be integral with the latter.An anodized film AOF of aluminum is also provided overlying the scansignal lines.

A dielectric film GI is employed to function as the gate insulation filmof each of the thin-film transistors TFT, and is formed to overlie thegate electrodes GT and scan signal lines. The dielectric film GI is madefor example of a silicon nitride film fabricated by plasma chemicalvapor deposition (CVD) techniques to a thickness of from 1,200 to 2,700Å (preferably 2,000 Å in this liquid crystal(display device). As shownin FIG. 9, the gate insulation film GI is so formed as to entirelysurround a matrix section AR with its peripheral portions removed awaythus allowing the external connection terminals DTM, GTM to be exposedto the outside.

The i-type semiconductor layer AS is used as a channel formation regionof each of two thin-film transistors TFT. The i-type semiconductor layerAS is formed of either an amorphous silicon film or a polycrystallinesilicon film of about 200 to 220 Å in thickness (about 200 Å thick inthis liquid crystal display device).

This i-type semiconductor layer AS is fabricated continuously to effectformation of the dielectric film GI made of Si₂N₄ for use as the gateinsulation films while varying feed gas components in the same plasmaCVD equipment without causing external exposure from such plasma CVDequipment.

In addition, an N(+) type semiconductor layer d0 with a chosen impurityfor ohmic contact such as phosphorus (P) doped therein at 2.5% is alsoformed continuously to a thickness ranging from 200 to 500 Å (about 300Å in this liquid crystal display device). Thereafter, the lowertransparent glass substrate SUB1 is removed from the CVD apparatus tothe outside to carry out photolithographical patterning processes sothat the N(+) type semiconductor layer d0 and i-type semiconductor layerAS are patterned into several independent islands.

The i-type semiconductor layer AS is also provided between bothintersections (crossover portions) of the scan signal lines with respectto image signal lines associated therewith. The i-type semiconductorlayer AS at the intersections acts to reduce electrical short-circuitingbetween the scan signal lines and the image signal lines at suchintersections.

A transparent pixel electrode ITO1 (corresponding to AL-P in FIG. 1)constitutes one of those pixel electrodes of the liquid crystal panel.The transparent pixel electrode ITO1 is connected to the sourceelectrode SD1 of each of the two thin-film transistors TFT. Due to this,even where a defect occurs at any one of such two thin-film transistorsTFT, the operation reliability may be guaranteed in a way such, that ifsuch defect can result in secondary operation failures or malfunction,then an appropriate portion is cut away, such as by laser light,otherwise no particular actions will be taken due to the fact that theremaining thin-film transistor TFT is operating normally. Additionally,it will rarely happen that both of two thin-film transistors TFTexperience defects at the same time, so that use of the redundancyscheme makes it possible to greatly reduce the possibility of occurrenceof point defects and/or line defects.

The transparent pixel electrode ITO1 is comprised of a first conductivefilm d1. This first conductive film d1 is made of a transparentconductive film (indium-tin-oxide or ITO film, or Nesa film) that wasformed by sputtering techniques to a thickness of from 1,000 to 2,000 Å(about 1,400 Å in this liquid crystal display device).

The source electrode SD1 and drain electrode SD2 of each of the twothin-film transistors TFT are provided so as to be spaced apart fromeach other on the i-type semiconductor layer AS.

The individual one of the source electrode SD1 and drain electrode SD2is arranged by sequentially laminating or stacking a second conductivefilm d2 and third conductive film d3, as seen from the lower layer side,in contact with the N(+) type semiconductor layer d0. The secondconductive film d2 and third conductive film d3 of the source electrodeSD1 are fabricated at the same process step or steps during formation ofthe second conductive film d2 and third conductive film d3 of the drainelectrode SD2.

The second conductive film d2 may be a chromium (Cr) film that is formedto a thickness of 500 to 1,000 Å (approximately 600 Å in this liquidcrystal display device). The Cr film is adapted for use as a so-calledbarrier layer to be described later, which prevents unwantedoutdiffusion of aluminum Al of the third conductive film d3 into theN(+) type semiconductor layer d0. The second conductive film d2 may bemade of, in the alternative, a Cr film, a film of high-melting-pointmetal (Mo, Ti, Ta, W, and the like), a layer of high-melting-pointsuicide (MoSi₂, Tisi₂, TaSi₂, WSi₂ or else), or any other similarsuitable materials.

The third conductive film d3 is formed by sputtering of aluminum Al to athickness of from 3,000 to 5,000 Å (about 4,000 Å in this liquid crystalpanel). Aluminum Al films are less in stress than chromium Cr films andfor this reason are capable of formation to large film thicknesses whilebeing arranged to reduce the electrical resistance values of the sourceelectrode SD1 and drain electrode SD2, as well as the image signal linesDL. The third conductive film d3 may alternatively be made from, otherthan ordinary aluminum, an aluminum containing therein silicon or copper(Cu) as additive materials.

After completion of the intended patterning processing of the secondconductive film d2 and third conductive film d3 using the same maskpattern, the N(+) type semiconductor layer d0 is removed by using thesame mask or alternatively using the second conductive film d2 and thirdconductive film d3 as a mask therefor. In single terms, certain portionsof the N(+) type semiconductor layer d0 which reside on the i-typesemiconductor layer AS other than those on the second conductive film d2and third conductive film d3 will be removed in a self-align fashion. Atthis time the N(+) type semiconductor layer d0 will be etched away sothat its thickness portions are all removed so that the i-typesemiconductor layer AS will likewise be etched away at the surfaceportion thereof; however, the degree of such etching treatment may becontrolled based on the length of the etching processing time.

The source electrode SD1 is connected to the transparent pixel electrodeITO1. The source electrode SD1 is arranged along the i-typesemiconductor layer AS's step-like difference portion (a step-likesurface configuration corresponding to a film thickness equivalent tothe total sum of the film thickness of the second conductive film d2 andthe film thickness of the anodized film AOF plus the film thickness ofthe i-type semiconductor layer AS as well as the film thickness of theN(+) type semiconductor layer d0). Practically, the source electrode SD1consists of the second conductive film d2, formed along the step-likedifference of the i-type semiconductor layer AS, and the thirdconductive film d3 formed to overlie this second conductive film d2. Thethird conductive film d3 of the source electrode SD1 is arranged topermit climbing,over the i-type semiconductor layer AS in view of thefact that the Cr film of the second conductive film d2 is incapable ofbeing made thicker due to an increase in stress and also is incapable ofclimbing over the step-like difference of the i-type semiconductor layerAS. In other words, thickening the third conductive film d3 improves thestep coverage. Since the third conductive film d3 is capable offormation to increased thicknesses, this significantly contributes toreduction of the resistance value of the source electrode SD1 (the samegoes with the drain electrode SD2 and/or image signal lines DL).

A protective film PSV1 is provided so as to overlie the thin-filmtransistors TFT and transparent pixel electrodes ITO. The protectivefilm PSV1 is formed in order to protect mainly the thin-film transistorsTFT against moisture; to this end, the one that is high in transparencyand has good resistance to humidity must be used therefor. Theprotective film PSV1 is made, for example, of a silicon oxide film orsilicon nitride film which is formed by plasma CVD apparatus to athickness of about 1 μm.

As shown in FIG. 9, the protective film PSV1 is formed to surround theentire matrix section AR, with its peripheral portions remove so as toallow the external connection terminals DTM, GTM to be exposed to theoutside and also with those portions removed which are used to connect acommon electrode COM (corresponding to the transparent electrode ITO-Cof FIG. 1) of the upper transparent glass substrate SUB2 to an externalconnection terminal extension lead INT of the lower transparent glasssubstrate SUB1 using silver paste. With regard to the thicknessrelationship of the protective film PSV1 versus the gate insulation filmGI, the former is made thicker in light of protection effectenhancement, whereas the latter is made thinner in view of thetransconductance gm of the transistors. Accordingly, as shown in FIG. 9.the protective film PSV1, which is high in protection effects, isfabricated so that it is larger in size than the gate insulation film GIto ensure that its periphery offers enhanced protectability over anextended area that is as wide as possible.

On the side of the upper transparent glass substrate SUB2, an opticalshield film BM is provided to prevent unwanted entry or incidence ofincoming external light into the i-type semiconductor layer AS that isused as the channel formation region.

The optical shield film BM is made of either an aluminum film orchromium film or any equivalents thereof, which, is high in opticalblocking ability. In this liquid crystal display device, the chromiumfilm is formed by sputtering to a thickness of 1,300 Å, more or less.Additionally this shield film is different from the shield film SHF inFIG. 1.

Consequently, the i-type semiconductor layer AS of thin-film transistorTFT is sandwiched between the overlying shield film BM and theunderlying gate electrode GT of slightly larger size so that suchportion will no longer receive any externally attendant natural lightnor any rays of backlight. As indicated by hatching in FIG. 19, theshield film BM is formed around a pixel; in other words, the shield filmBM is formed to have a lattice or grid-like pattern (known as blackmatrix), which grid defines by partition the effective or net displayarea of a single pixel. Use of such shield film BM makes the contour ofeach pixel clear and “crisp” to thereby improve the contrast. Insummary, the shield film BM functions to offer optical shielding withrespect to the i-type semiconductor layer AS while simultaneouslyserving as the black matrix for improvement of the contrast by providingpartitions between color filters FIL(R), FIL(G), FIL(B).

In addition, since part of the transparent pixel electrode ITO1 whichopposes the root-side edge portion in the rubbing direction is opticallyblocked or “shuttered” by the shield film BM, any domains that can occurat such part are invisible, which in turn ensures that the displaycharacteristics are free from any possible degradation.

Where necessary, the backlight may alternatively be attached to theupper transparent glass substrate SUB2 while allowing the lowertransparent glass substrate SUB1 to be on the observation side (externalexposure side).

The shield film BM is also formed at the peripheral section to have aflat rectangular frame-like pattern which resembles a window frame inplanar shape and is formed continuously with the pattern of the matrixsection that has a plurality of openings or apertures in the form ofdots. The shield film at this part is similar in function to the shieldfilm SHF. The shield film BM at the periphery is extended beyond thestrip spacer SPC-S toward the outside of the seal material SL, therebyprecluding undesired entrance or “invasion” of leakage light, such asreflection light otherwise occurring in actually implemented equipment,such as personal computers or the like. On the other hand, this shieldfilm BM is forced to reside inside of the edge of the upper transparentglass substrate SUB2 by approximately 0.3 to 1.0 mm and is formed toavoid passing through cut regions of the upper transparent glasssubstrate SUB2.

The color filters FIL(R), FIL(G), FIL(B) are comprised of a dyeing orstain base made of a resin material such as acrylic resin or the likewith color development effected thereto using dyestuff. Note that thecolor filter FIL(B) is not depicted in FIG. 10A, 10B or 10C. These colorfilters FIL(R), FIL(G), FIL(B) are formed at specified positionscorresponding to pixels to have a stripe shape, and are individuallycolored into respective colors of red (R), green (G) And Blue (B). Thecolor filters FIL(R), FIL(G), FIL(B) are formed to have a predefinedsize large enough to cover all of the transparent pixel electrodes ITO1whereas the shield film BM is formed inside of the peripheral edges ofsuch transparent pixel electrodes ITO1 to thereby overlap those edgeportions of the transparent pixel electrodes ITO1.

The color filters FIL(R), FIL(G), FIL(B) may alternatively be formed inthe following way. First, a chosen dyeing base is formed on the surfaceof the upper transparent glass substrate SUB2; then, certain portions ofthe dyeing base residing in specified regions other than the red-colorfilter formation regions are photolithographically removed. Thereafter,the dyeing base is dyed with red dyestuff and then fixing or stickingtreatment is carried out thus forming the red color filters FIL(R).Next, similar treatment processes are performed to sequentially form thegreen color filters FIL(G) and blue color filters FIL(B).

A protective film PSV2 is provided for preventing the dyestuff used todye the color filters FIL(R), FIL(G), FIL(B) into different colors fromattempting to leak into the liquid crystal layer LC. This protectivefilm PSV2 is made of transparent resin materials typically includingacrylic resin or epoxy resin or the like.

A common transparent pixel electrode ITO2 opposes transparent pixelelectrodes ITO1 that are provided on the lower transparent glasssubstrate SUB1 in units of pixels, wherein the optical state of theliquid crystal layer LC varies or changes in response to a voltagepotential difference (electric field) between each pixel electrode ITO1and common transparent pixel electrode ITO2. This common transparentpixel electrode ITO is arranged to receive a common voltage Vcom asapplied thereto. Although the common voltage Vcom is set here at anintermediate potential between a low-level drive voltage Vdmin andhigh-level drive voltage Vdmax applied to the image signal lines, if thepower supply voltage of an integrated circuit for use in image signalline drive circuitry is required to decrease down to about half then anAC voltage may be applied thereto. Additionally, part of the planarshape of the common transparent pixel electrode ITO2 is shown in FIG. 9.

It should be noted that the gate terminals GTM are composed of achromium Cr layer g1 having excellent adhesiveness with a silicon oxideSIO layer and having a higher resistance to electrolytic corrosion thanaluminum Al, and a transparent conductive layer d1 lying at the samelevel as the pixel electrodes ITO1 (same layer, simultaneousfabrication) while protecting the surface of the former. Also note thatconductive layers d2 and d3 that are formed on the gate insulation filmGI and sidewalls thereof are the ones which reside as a result ofcoverage of such regions by a photoresist to preclude the conductivelayers g2 and g1 from being etched away due to presence of pinholesduring etching of such conductive layers d2 and d3. Additionally the ITOlayer d1 that is designed to extend in the right direction beyond thegate insulation film GI is for further enhancing such similar remedy.

As shown in FIG. 9, the drain terminals DTM constitute a terminal groupTd (suffix omitted), which terminals are arranged to further extendbeyond a cut line CT1 of the lower transparent glass substrate SUB1 andall of which are electrically short-circuited together by a lead SHd inorder to prevent electrostatic breakdown or destruction during themanufacturing processes.

The drain terminals DTM are each formed of two layers including achromium Cr layer g1 and ITO layer d1 for the same reasons as in thegate terminals GTM and are connected to an image signal line DL at aspecified part from which the gate insulation film GI has been removedaway. The semiconductor layer AS is formed to overlie the edge of thegate insulation film GI for image-signal etching the edge of the gateinsulation film GI into a tapered shape. Of course, the protective filmPSV1 for providing interconnection with external circuitry has beenremoved at locations overlying the drain terminals DTM.

FIG. 11 is an exploded perspective view of the overall structure of adirect-view liquid crystal display device employing the liquid crystaldisplay device in accordance with the present invention.

The liquid crystal display device shown herein represents one actuallyimplemented structure of a liquid crystal display device (liquid crystaldisplay module) with its liquid crystal panel and circuit boards plusbacklight unit along with other components associated therewithassembled together integrally.

In FIG. 11, “SHD” designates an upper frame (also known as a shieldcasing, or metal frame) made of a metal plate; WD denotes a displaywindow; INS1-3 indicate dielectric sheets; PCB1-3 represent printedcircuit boards (PCB1 is a drain-side circuit board for use as an imagesignal line driver circuit board, PCB2 is a gate-side circuit board, andPCB3 is an interface circuit board); JN1-3 are joiners for electricalconnection among the circuit boards PCB1-3; TCP1, TCP2 are tape carrierpackages; PNL denotes a liquid crystal panel using the pole spacers andstrip spacer that have been described in the embodiment for setup of aprespecified cell gap; POL denotes upper polarizer plate; GC denotes arubber cushion; ILS denotes an optical shielding spacer (correspondingto the shield film SHF in FIG. 1); PRS denotes a prism sheet; SPSdenotes a diffuser sheet; GLB denotes a light guide plate; RFS denotes areflection sheet; MCA denotes a lower frame formed by all-at-a timemachining of resin (also called a lower casing, or mold frame); MOdenotes an opening or aperture of the MCA; BAT denotes both-sideadhesive tape, wherein diffuser plate members are laminated over oneanother to assemble the liquid crystal display device MDL. In addition,a light source assembly consisting of a fluorescent tube LP andreflector sheet LS is disposed along one side of the light guide plateGLB, which is electrically fed from a backlight power supply unit, notshown, via a lamp cable LPC that is extended from the rubber cushion GCportion as provided at the edge of the fluorescent tube LP. The lightguide plate GLB and the light source assembly makes up the backlight BL.Additionally, the light source assembly may alternatively be providedalong two sides or four sides of the light guide plate GLB.

This liquid crystal display device (liquid crystal display module MDL)has an enclosure or housing that consists essentially of two kinds ofreceiving/retainment members, which constitute the lower frame MCA andupper frame SHD, and is arranged so that the dielectric sheets INS1-3and circuit boards PCB 1-3 plus liquid crystal panel PNL are immovablyreceived therein while engaging with the upper frame SHD and the lowerframe MCA with the backlight including the light guide plate GLB andothers.

Mounted on the image signal line driver circuit board PCB1 are severalelectronics components including but not limited to integrated circuitchips for use in driving respective pixels on the liquid crystal panelPNL, whereas the interface circuit board PCB3 mounts thereon integratedcircuit chips for use in receiving image signals from an external hostcomputers) and also for receiving control signals such as timing signalsand the like, more than one timing converter (TCON) for generation of aclock signal or signals by processing the timing, one or morelow-voltage differential signal chips, and other electronic parts orcomponents typically including capacitors and resistors or anyequivalents thereto.

A clock signal which is generated and issued from the timing converteris then supplied to built-in driver circuit chips (integrated circuitchips) mounted on the image signal line driver circuit board PCB 1.

The interface circuit board PCB3 and image signal line driver circuitboard PCB1 are multilayer printed circuit boards, wherein the clocksignal lines CLL are formed as inner leads of the interface circuitboard PCB3 and image signal line driver circuit board PCB1.

It is noted that the drain-side circuit board PCB1 for use in drivingthe TFTs and the gate-side circuit board PCB2 plus interface circuitboard PCB3 are connected by the tape carrier packages TCP1, TCP2 to theliquid crystal panel PNL while using the joiners JN1, 2, 3 to connectbetween respective circuit boards.

With this liquid crystal display device, it becomes possible to obtainhigh-quality image displayability with on-screen visual irregularitiesbeing suppressed or minimized.

FIG. 12 depicts a perspective view of a notebook personal computer (PC)also embodying the invention, which employs the liquid crystal displaydevice shown in FIG. 11.

This notebook computer (handheld or mobile PC) consists essentially of akeyboard unit (main body) and a display unit as foldably coupled viahinges to the keyboard unit. The keyboard unit has a keyboard on its topfaceplate and contains therein a host (host computer) along with signalgeneration functions achieved by a microprocessor such as a CPU or thelike, while the display unit has the liquid crystal panel PNL assembledtogether with a PCB mounting thereon driver circuit boards FPC1, FPC2and controller chip TCON as well as an inverter power supply board IVused as the backlight power supply, which are received near or aroundthe liquid crystal panel PNL.

Each of the electronic equipment with the liquid crystal display devicebuilt therein is capable of offering enhanced displayability ofhigh-quality images with visual irregularities greatly suppressed oreliminated because of the fact that its liquid crystal panel's cell gaphas less variation.

As apparent from the foregoing, according to the present invention, itis possible to provide a high-quality liquid crystal display device withreliability increased, wherein since the columnar or pole-like spacersare provided at selected positions excluding the pixel electrodes in adisplay area while at the same time providing the zonal or bandstrip-shaped spacer at the sealing portions around the display areabetween two insulative substrates for permitting deposition or coatingof a seal material at outer edges of this strip spacer which is laterhardened, it is possible to uniformly control the cell gap over almostthe entire screen area. In addition, because a liquid crystal materialconstituting the liquid crystal layer will no longer come into contactwith the seal material being used, contamination of the liquid crystalmaterial due to such seal material may be eliminated. Furthermore, useof no fillers for the seal material makes it possible to avoid damagesuch as undesired open-circuiting of electrode extension leads.

What is claimed is:
 1. A method for forming a liquid crystal displaydevice, comprising the steps of: forming a metal film over a drivesubstrate; patterning said metal film to form at least one pixelelectrode and an optical shield film, said optical shield film beingprovided outside of a pixel electrode area and having a width greaterthan a width of each of said pixel electrode; depositing a resin oversaid patterned metal film; patterning said resin to form at least onepole spacer and a strip spacer, said strip spacer surrounding said pixelelectrode area and having a width greater than a diameter of each ofsaid pole spacer and being formed over said optical shield film;supplying liquid crystal material into an inside space which issurrounded by said strip spacer; disposing a common substrate over saiddrive substrate; and filling a sealing material at outer edges of saidstrip spacer for fixing said drive substrate and common substrates. 2.The method according to claim 1, wherein said resin depositing iseffected by spin coat.
 3. The method according to claim 1, wherein saidresin is a photolithographically fabricated resist.
 4. The methodaccording to claim 1, wherein said pixel electrode is a reflective pixelelectrode.
 5. A method for forming liquid crystal display device,comprising the steps of: forming a metal film over a drive substrate;patterning said metal film to form at least one pixel electrode and anoptical shield film, said optical shield film being provided outside ofa pixel electrode area and having a width greater than a width of eachof said pixel electrode; depositing a resin over said patterned metalfilm; patterning said resin to form at least one columnar spacer and azonal spacer, said zonal spacer surrounding said pixel electrode areaand having a width greater than a diameter of each of said columnarspacer and being formed over said optical shield film; supplying liquidcrystal material into an inside space which is surrounded by said zonalspacer; disposing a common substrate over said drive substrate; andfilling a sealing material at outer edges of said zonal spacer forfixing said drive substrate and common substrates.
 6. The methodaccording to claim 5, wherein said resin depositing is by effected spincoat.
 7. The method according to claim 5, wherein said resin is aphotolithographically fabricated resist.
 8. The method according toclaim 5, wherein said pixel electrode is a reflective pixel electrode.